LED lighting may generally provide advantages in energy conservation, environmental protection, controllable lighting, solid state lighting, and long operational lifetime. LED lamps thus have been widely used in various areas for public, commercial, and/or indoor lighting.
Often, LED lamps may have lamp-head structures generally-designed similar to incandescent lamps, energy saving lamps, and other conventional lamps. Presumably, LED lamps may be used to directly replace other conventional lamps by an easy installation without changing original structures of a lighting system including other conventional lamps.
However, when other conventional lamps are replaced by conventional LED lamps, dimming feature of the LED lamps may not be applied, because those other conventional lamps do not include any dimmers to implement the dimming feature of the replaced LED lamps. To add a dimmer in those conventional systems can increase cost in use and can require complicated, additional installation.
In some LED lamps, a switch may be used to replace a dimmer to control brightness of an LED lamp. One method of using a switch for dimming control includes a stepless dimming process. When a user presses the switch for a first time, lighting brightness of the lamp may gradually change from a minimum brightness level to a maximum brightness level, which may take a few seconds. During this gradual changing process, if the user presses the switch for a second time, the lamp may be turned off and the brightness level at this point may be memorized by the LED lamp. When the user presses the switch for a third time, the lamp may provide the previously-memorized brightness. When the user presses the switch for a fourth time, the lamp may then be turned off. When the switch is pressed again, the process may be repeated. In some cases, after pressing the switch for the first time, the user may not press the switch during the time interval for gradually changing brightness from the minimum level to the maximum level. The lamp may then be operated at the maximum brightness level until the switch is pressed again to turn off the lamp.
In another method of using a switch for dimming control, a brightness level may be selected from several set-brightness levels. In a two-level dimming process, the lamp may be operated at a first set-brightness level when the switch is pressed for a first time. When the switch is pressed for a second time, the lamp may be turned off. When the switch is pressed for a third time, the lamp may be operated at a second set-brightness level. When the switch is pressed for a fourth time, the lamp may be turned off. When the switch is pressed for a fifth time, the lamp may be operated at the first set-brightness level, which is the same as for the step when the switch is pressed for the first time. Such a process may then be repeated.
In other cases, the brightness level may be selected using a dimming chip or a microcontroller (MCU). Such designs, however, require complicated circuit and increase the cost for the LED lamps.